# Test Writer Vitest Rtl

> Write unit and component tests using Vitest and React Testing Library, or integration tests for API routes/Server Actions. Use when asked to "write tests", "add test coverage", or "test this function/component".

- Skill: `gabrielmoreira/test-writer-vitest-rtl` (Agent Skill)
- Install (CLI): `npx skillmds@latest add gabrielmoreira/test-writer-vitest-rtl`
- Raw SKILL.md: https://api.skillmd.com/api/skills/gabrielmoreira/test-writer-vitest-rtl/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: gabrielmoreira (https://skillmd.com/u/gabrielmoreira)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/gabrielmoreira/test-writer-vitest-rtl

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# Test Writer Skill (Vitest + RTL)

## Process

1. Identify what's being tested: pure function → unit test in `src/**/*.test.ts` next to the source file; component → `*.test.tsx` next to the component; API route/Server Action → integration test in `src/**/__tests__/` or co-located.
2. Cover, at minimum: the happy path, one validation/error path, and any edge case explicitly mentioned by the user or visible in the code (empty arrays, null, boundary numbers).
3. For components, query by accessible role/label/text (`getByRole`, `getByLabelText`) — fall back to `data-testid` only when there is no accessible query available.
4. For async behavior, use `findBy*` queries or `waitFor`, never arbitrary `setTimeout`.
5. For Server Actions/API routes, mock the database layer at the module boundary (e.g. `vi.mock('@/server/db')`) rather than hitting a real database.
6. Run `pnpm test <path>` after writing to confirm the test passes (and would have failed before the fix, for regression tests).

## Test skeleton

```ts
import { describe, it, expect, vi } from "vitest";

describe("<unit under test>", () => {
  it("does the expected thing on the happy path", () => {
    // arrange, act, assert
  });

  it("handles the error/edge case", () => {
    // arrange, act, assert
  });
});
```

## Checklist
- [ ] Happy path covered
- [ ] At least one failure/edge case covered
- [ ] No arbitrary `setTimeout`/sleep in async tests
- [ ] Mocks isolated at module boundary, not deep internals
- [ ] `pnpm test` passes locally